Helicopter transmission



July 15, 1952 A. E. KlLPr-:LA

HELICOPTER TRANSMISSION 2 SHEETS- SHEET l Filed Aug. 9, 1944 July 15, 1952 A. E; KILPELA HELICOPTER TRANSMISSION 2 SHEETS--SHEET 2 Filed Aug. 9, 1944 oww. l!

Kriz/enfer.' Q'no E24/vega,

Patented July l5, 1952 UNITED sTATEs HELCOPTER TRANSMISSIN Ano E. Kilpela, Detroit, Mich., assigner to Borg- Warner Corporation, Chicago, Ill., a corporation of Illinois Application August 9, 1944, Serial No. 548,639

7 Claims.

This invention relates to transmission gearing and it is particularly directed totransmissions for driving the main supporting shaft and rotor blades of a helicopter or similar aircraft wherein the rotational axis of the assembly is vertically disposed.

It is one of the principal objects of this invention to simplify the construction of a transmission gearingof the character contemplated herein, and to improve the efficiency, operation and dependability of such transmission gearing.

It is also one of the principal objects of this invention to provide an assembly of the character herein contemplated wherein disconnection of the engine or prime mover from the transmission may be `readily accomplished so that the motor may be or idled or tested without driving the rotor or operating the shaft that supports the same and transmits torque thereto.

Another principal object hereof resides in the provision of means, preferably comprising a positive one-way clutch that will permit the main or sustaining rotor to idle independently of the power means to effect gradual descent and a safe landing of the helicopter in the event of failure or stalling of the engine. In this connection, provision is made in the present structure whereby upon failure of the engine the tail or torque control will be operated during rotation of the main or sustaining rotor through instrumentalities interposed between and operatively connecting the main rotor shaft and the take-off shaft that drives the tail rotor. v

A still further object of the present. invention is to provide a lubricating system, preferably of the forced-feed or pump type that effects a positive distribution of lubricant to the various instrumentalities of the transmission. The pump for discharging the pressure lubricant into the various ducts or passages is so constructed and located in the assembly that it is readily accessible and may be removed with a minimum of labor. The pressure lubricant also provides the means for actuating a hydraulic piston for effecting engagement of the members of a clutch that is interposed in the transmission assembly.

It is preferred to accomplish the numerous objects of the invention contemplated herein and to practice the same in substantially the manner hereinafter fully described and as more particularly pointed out in the appended claims. Reference is nowmade to the accompanying drawings forming a part hereof wherein:

Fig. 1 is a vertical axial section of an assembly embodying theinstrumentalities of the present 2 invention, the structure being particularly adapted for use in aircraft of the helicopter type;

Fig. 2 is a fragmental sectional view on the plane of line 2--2 on Fig. l, drawn to an enlarged scale;

Fig. 3 is an enlarged sectional view taken on the plane of line 3 3 on Fig. 1;

Fig. 4 is a horizontal sectional view ytaken on the plane of line 4 4 on Fig. 1 looking in the direction of the arrows; and

Fig. 5 is a horizontal sectional view taken on the plane of line 5--5 on Fig. 1 looking in the direction of the arrows.

The drawings are to be understood as being more or less of a schematic character for the purpose of disclosing a typical or preferred form of the improved transmission gearing contemplated herein, and in these drawings likereference characters identify the same parts in the several views. n

The form of this invention which is shown` in the drawings preferably embodies a suitably shaped housing l0 that is anchored in any suitable manner to the body or framework of an aircraft such as a helicopter, and there are axially aligned bearings II and I2 respectively in the lower and upper portions of said housing'. The drive shaft I3 is rotatably supported in the lower bearing II, and the driven shaft I4 for the sus-A taining rotor is rotatably supported in the upper bearing I2. These shafts I3 and I4 are disposed in axialalignment with each other and there is a speed reduction and torque multiplication of the desired ratio between said shafts that is effected by means of a transmission gearing assembly that operatively connects the portions of the shafts within the housing I0.

The drive shaft I3 is connected to the engine shaft `or other prime mover by means that comprise the flangeV I5 splined to the lower end portion of said shaft I3 that is projected below the housing and the bearing Il, said flange being maintained in place by the usual nut and retainer disc arrangement. Suitable connection (not shown) is made between the driven shaft I4 and the sustaining rotor of the helicopter that operates above the body of the aircraft. Within the housing Illthe ends of the drive shaft I3 and driven shaft I4 terminate adjacent each other, and said end portions of these shafts are journaled in bearings I3a and I4a respectively.

The' instrumentalitiesthat operatively connect the drive shaft I3 to the driven rotor shaft I4 are preferablya transmission gearing comprising adrive pinion I6 that is loosely mountedupon 3 the upper portion of the drive shaft I3 beneath the bearingsf I3a, the said pinion being formed upon one end portion of a sleeve II that is provided With an enlarged bell-shaped, lower portion IB disposed in spaced relation laterally of drive shaft I3 and forms a portion of a clutch. The sleeve is freely rotatable relative to drive shaft I3 and rests upon "a washer Ila that is seated on a shoulder I3b on the power shaft I3, the washer being maintained in place by a snap-ring I1b.

The clutch, which is preferably of the multiple plate friction type, comprises the drum I9 that surrounds the portion I8 of the sleeve I1 and is.

disposed in spaced relation thereto, said drum being supported and driven by the marginal toothed portion of a lateral flange preferably integral with drive shaft I3. Internal splines 2I are formed on drum I9 to drive friction plates 22, and there are external splines 23 on the sleeve I8 to coact and rotate withthe driven friction plates 24 that Yare alternately disposed 'between the friction drive 'plates'22.

An annular pressure plate 25, operating in the drum I9, transmits force to engage the friction plates 22 and 24, the force being derived from an oil-pressure actuated pist`on'26 operating against the pressure plate '25. 'An' annulus 21, driven by splines 2I on the drum, is positioned above the friction plates 22 and 24, and together with a snap ring 28, provides an abutment'or stop that opposes the action of the pressure plate 25 and piston 26 and limits 'the movement of the friction clutch plates axially of the drive shaft I3. A heavy coiled Vspring ISU. surrounds the drive or power shaft I3 between the sleeve-'supporting washer I1a and the inner lower portion of piston 2'6 to urge the piston downward ina direction to disengage the clutch plates 22 and 2'4.

Pressure fluid, preferably lubricating'oil'under pressure, is supplied to a chamber 29, that is coaxial with the clutch back of thepiston26, by a pump 30 that surrounds a sleeve |511r splined on the lower portion of drive shaft I3 and' which is abutted by the cylindrical portion of' flange VI5 i to rotate withsaid shaft and flange. The pump 30 has its movable member secured to the sleeve I5a by a key 3I. The pump which'i's'below the bearing II is held in place by a flange in which may be incorporated a stuing member' or oil seal ring 32 that is engaged bythe sleeve I5a, thus providing an arrangementthfat permits the pump to be readily removedby dismountng the flange I5 and the adjacent sealingY flange without dis'-v turbing the bearing I I. l K I The oil for the pump passes from the sump 33 in the bottom of housing I0 through a strainer 34 and passageway 35 to thesuction port of the pump. and it discharges under pressure into a feed passageway 36 having a branch 31 communicating with an annular channel 38 surrounding drive shaft I3 above the bearing II, and thence through lateral ports 39 into the bore 40 of said drive shaft. One or more oblique passages 4I in shaft I3 establish communication between the piston chamber 29 and the shaft bore 40 so that the pressure fluid is effective upon the piston 26 to frictionally engage the plates 22 and 24 which will operate this friction clutch when the oil pressure overcomes the urge of the 'spring I'a. f Y

A portion of the oil under pressure is led by passages 42 away from the annular channel 38 tolubricate parts 'of the transmission "assembly to b later'describedherein. The transmission drive pinion 'I'6"th'atis' op'- eratively connected to the drive shaft I3 when the friction plates 22 and 24 of the clutch are engaged, is meshed with a plurality of fixed gears 43 mounted for rotation upon stationary countershafts 44 that are secured by pins 45 to a ring portion 46 mounted on an inwardly projecting portion of housing I. The hubs of gears 43 are elongated and are formedwith pinions 4l that mesh with an internal gear '48 formed in the annular flange 49 of a large disc 50 that is integr-al with a central sleeve 52 surrounding a reduced lower portion of the rotor or driven shaft I4. A radially disposed bracket portion 53 has openings into which the upper ends of countershafts 44 are inserted, and the portions 53 and 46 are integral with each other and form a cage for the shafts 44. 'Ihe cage comprising the portion 53 and 46 is fixed with respect to the housing I0 by any suitable means and including the shafts 44 which at their lower ends extend into suitable openings in the housing. The central sleeve 54 of the cage, as shown, surrounds the inner bearings I3a and I4a of the respective shafts I3 and I4. Y

The internal gear 48, together with its 'sleeve 52, is connected to the rotor shaft I4 by means of a driving device that is preferably a positive one-way clutch assembly of the toothedftyp'e. One member of this clutch comprises an annular collar 55 surrounding the sleeve '52 andmovable in an axial direction thereon through a helically splined connection 56 therewith. Thiscollar'is urged upward against a stop-ring 51 by'the'thrils't due to the helically splined connection wherrthe engine is driving and by helical spring58 inter-Y posed between the lower portion of saidcollar and the upper face' of the disc 50 that carries the internal gear'48. The upper'edge of collar 551s castellated to provide axially extending teeth 69 that mesh with similar axiallyV extending teeth 60 on the other or opposing member 6I of the clutch. This other clutch member 6I comprises theglowe'r hub portion of a large bevel gear 62 thats'u'rrounds the rotor shaft I4' above the positive clutch and has an upperelon'gated sleeve portion 631 that has a splined connection-64 with said rotor shaft so that it turns therewith. The' sleeve 63.v gear 62 and its hub provide theoutput member ofV this clutch and transmission assembly. The upper end of the sleeve 63 abuts the bearing I2'andthe lower ends of the splines rest upon a split rln'gl65 that is sprung into an annular groove6'6- inthe' adjacent portion of the rotor shaftv I4.

The brake drum 61 is anchored to the web-'68 of the bevel gear 62 in the manner shown andlt is surrounded by a friction brake-band69 (fg 4')- that is provided with the usual terminal lugs 1,6 and 1'I between which there is interposeda coiled spring 12 that is under compression to normally urge the lugs in opposite directions away from each other to loosen'the' brake-band 69. Lug 1I is engaged by theinnerend of a stop bolt 13 that is screwed into and through a'threadedfbo'ss'll and it has an outer slotted end' projected through the housing I0 to'permit longitudinal adjustment thereof for taking up wear in bandV 69. l"I'heother lug 1D is engaged by the inner end of aA plunger 15 vhaving reciprocating longitudinal movement in a bearing 16, such movement being keffected by arotary reciprocableedge cam 1'I thatiengages the other or outerend of said'piunger l152' cam 11 is secured to the inner-end of airockspindle 18 disposed with its'axis transverseto' thejaxlsof plunger 15 andmountedjjin a b'earingzboss's formed integral withthe adjacent portionofti'e housing. .The outer end of" this spindle thatprojects beyond the housing is provided with a crankarm 80 to which manually operated means are connected for rocking' the spindle to operate the brake band 6g to. constrict it upon or loosen it from the brake-drum 61. When the brake'struc ture is tightened during operationfof thev rotor shaft, the rotation of the clutchmember G will be 4arrested together with the rotor shaft towhich it-'isvsplinecll 1i Y y y rThe bevel gear e2 meshes with a bevel` pinion 8l .that is formed upon a shaft 82 which is disposedtvvith itsr axisoblique to the axis of .rotation ofthe transmission assembly, and. it is journaled byfbearings 83 and 3d inahollow boss 35 preferably cast with the housing 1B.' One end of this shaft 82 is provided with lan attaching flange 8S having internal splines for operatively connecting' the shaft to the instrumentalities (not shown) for transmitting torquato the control rotor or other devices of the helicopter or -other'aircraft Pressure lubricant. from the pump 3l is fed to. thevarious operatingfparts of the transmission assembly through an oil-distributing system of ducts and the like. The ducts ft2 are adapted to discharge into the' bores 83er theccuntershafts M of the transmission assembly and such discharge is controlled by spring-seated outward pressure valves 89 in the bottoms of the bores 8E so that the oil will not be admitted to such bores 8,/8 until the pressure of the lubricant is Sufficient to overcome the tension of the control springs S that urge the valves into theirr closed positions. Thereafter'the oil will -be discharged through a pluralityof lateral ports Si to lubricate the adjae cent members of the assembly. Interposed be.- tween the ends of the power shaft I3 and rotor shaft ld, there is a spring-seated outward pressure valve 92 that controls the flow of lubricant from theshaft bore 4l) into the bore -93 vin the lower portion of said rotor shaft. This valve 92 operates as a pressure reliefvalve in the same manner as Valve 89 to permit passage of lubricant into rotor shaft bore 93 when the pressure of the lubricant overcomes the urge of thevalve seating spring 94, and the oil will then be distributed to the working parts of the adjacent structurev through ducts S5.

The hydraulically operated friction clutch assembly that surrounds the power shaft I3 is manually controlled by instrumentalities that are disclosed in Fig. 5, wherein it will be seen that the annular lubricant chamber 38 communicates with a lateral passage 96 leading to a discharge port 91 in an elongated hollow boss 98. A cupshaped sliding valve 99, which controls communication between the lateral passage 9S and the discharge port 91, is adapted to be moved by the pressure lubricant to uncover the port so that the lubricant will overflow or spill back into the oil sump 33 when the lubricant/is not needed to operate the clutch. Y A plunger rod lill), operated by a bell-crank Ii, is adapted for longitudinal reciprocable movement in the hollow boss 98, and at its inner end said rod itil is provided with a stamped cup 192 to seat an end of a coiled spring |03 that has its other end seated against a follower E04. Between the follower and the slide valve SS there is a spring |05 of lighter tension than the spring it, and at the end of the bore of the hollow boss 98 there is a stop |56 that arrests movement of the valve to the right (Fig. 5). When the friction clutch is released, the pressure lubricant will be by-passed through the port 91 and returned to the sump, and when it is desiredv to utilize thep'ressure lubricant to :operate the-piston 26 and frictionallyengage the mem'-vr bers of thisY vclutch the bell-crank is manually rocked to push .theplunger rod H10 inwardnso that the heavier spring BB3 will yovercome the lighter spring |65 to such an extent that follower` |04 will :contact valve [919 and forcethe valve against the stop |05 and close the discharge or overflowv port 91., The pressure which iscon-g trolled by valve $2 will then build up inthe clutch` chamber 29 and Will be effective luponthe piston 2E to force it vupward and ieffect frictional engagement of the clutch plates 22 and ,24 which; willoperate the transmission gearing to rotate-y the ,rotor `shaft lli.

The pressure. will; likewise open valves 89 and 92 to lubricate the various moving parts. f

The function of light spring I G5 isl tomaintain a slight pressure for lubrication purposes `when the clutch is disengaged. Y

. While this invention has been described in dee tail in its present preferred forni or embodiment,

it will be apparent to persons skilled in the art.: after understanding the improvements contemf, plated herein, that various changes and modications may be made therein without.y departing from the spirit or scope thereof. Itis aimed in theappended claims to cover all such changesf4 and modifications. l

I claim:

l. A transmission for driving the -lnain rotcjruy and control rotor of a helicopter,comprisingai rotatable power shaft and a driven main rotor shaft; a geartrain for effecting torque multiplication between'said shafts; a clutch for ve'ffecting one-Way driving connection betweens'aid gear train and said main rotor shaft, said Aclutch comprising a first toothed member splined to said rotor shaft; a second toothed member ro' tated by the output member of the gear train and being yieldably urged toward the first toothed member to mesh with the teeth thereof; a bevel gear carried by the first toothed member a power take-off pinion meshed with said bevel gear for driving a control rotor of the helicopter; and'a manually operated brake assembly connected withI said first toothed member. Y Y

2. A'transmission as defined in' claim 1, where-- tary shaft; a second toothed member splined to the output member of the gear train; a spring normally urging the second toothed member into meshed engagement with the rst toothed member; a bevel gear formed integral with the first toothed member; a power take-off pinion meshed with said bevel gear for driving a control rotor of the helicopter; a friction brake drum secured to said bevel gear; a band surrounding said drum; and manually operated means for effecting frictlonal-engagement of the band with the drum.

4. A transmission for driving the main rotor and control rotor of a helicopter, comprising a ,rotatable power shaft and a driven main rotor o shaft; a multiple countershaft gearing for eifectp in: torque multiplication between said shafts; la clutch for etlecting one=way driving 'connectionbetween said gear train and said main rotor shaft. saidL clutch comprising a `first toothed member splined .to said rotor shaft; a second toothed member splined to the 'output member of the gearing Aand being yieldably urged toward the first toothed member to mesh with the teeth thereof; a bevel gear formed integral with the mst toothed member; an oblique web between the bevel "gear and the first toothed member toposi tion-said bevel Vgear in a plane above said memL ber; a power take-olf pinion meshed With said bevel gear for driving a control-rotor ofthe heli-` copier, the axis of said pinion being oblique'to the axis of the bevel gear; and a manually op; erated brake assembly connected with saidflr'st toothed member'.

5.'In apow'er transmitting mechanism for a helicopter, a drive shaft, 'adrivenrotor shaft for driving the rotor of the helicopter, a positive one-Way verrunning clutch mechanism adapted to connect said shafts to permit overrunnihg of the rotor shaft, said clutch comprising a toothed collar splined to the rotor shaft and having abra-lie drum connected to said colla-r, an axially movable toothed member drivingly conncte'd to the drive shaft and engageable with the toothed collar, and manually operable fric# tion engaging means coacting with the brake drum and engageable at will for arresting the rotation of the toothed collar to thereby prevent overrunning of the rotor shaft when the hlioopter is grounded and said drive shaft is stati'onary.

6. In a power transmitting mechanism for a helicopter, a drive shaft, adrlven rotor shaft for drivingthe rotor of the helicopter, a positive one- Way overrunnin'g clutch mechanism for connecting said shafts to permit oveirurining of said rotor shaft, said clutch comprising a first toothed member secured to the rotor shaft and having a brake drumconnected to said member, a second toothed member rotated by the drive shaft, means' for yieldably urging the second toothed member into operative engagement with the rst toothed member, and manually operated engaging means coacting with the brake drum and ngag'e'abl at member to prevent overrunning of the' rotor shaft when the helicopter is grounded and said drivl shaft is stationary.

'7. Inra power transmitting mechanism for n. helicopter, a', `rr'itary drive shaft, a driven vrotor shaft for driving the rotor of the helicopter, l. positive on'e-way lovexxunning clutch mechanism for connecting lsaid shafts 'and `permitting: kover running of said driven rotor shaft, said clutch comprising a toothed collar splined to the rotor shaft and having' a brake drum connected to said collar, an axially movable toothed member, a helicalV splined connection operatively connecting said vaxially movable toothed member and said drive shaft, means biasing said 'axially movable member into operative engagement with the toothed collar, the directionxof inclination of the,

splines of said connection .being such as to assist said biasing means lin eieo'ting engagement of the toothed collar and axially movable member when said drive shaft is rotated, and manually operable friction means operable at will and coacting with'the brake drum for arresting rota-'- tion of the toothed collar to prevent free rotation of the rotor shaft when said drive .shaft is stationary.

ANO E.

REERENGES Gi'iiE The following references are' of record lin the aie of this patent: U'ITED STATES PA'N'rs 

